As a conventional technique, for example, the air purifier described in Patent Literature 1 is known. The air purifier according to the conventional technique includes means for detecting a concentration of pollutants contained in air and means for controlling a volume of air blown out. The air purifier monitors the concentration of pollutants while circulating air in a room, and thereby catches a pollution source and changes a fan operation level (blown air volume) to reduce time required for purification of the room.
As another conventional technique, for example, the air purifier described in Patent Literature 2 is known. The air purifier detects a human existing in a room and controls a direction of blowing of air so that the air does not blow onto the human. Consequently, the other convention technique prevents air blown from the air purifier from giving a feeling of discomfort to a human.